It is common for late diagnosed autistics to have received an earlier misdiagnosis of borderline personality disorder (BPD).How and Why is Autism Spectrum Disorder Misdiagnosed in Adult Patients? : From Diagnostic Problem to Management for Adjustment, Takara, Kondo, & Kuba, 2015Missed diagnoses and misdiagnoses of adults with autism spectrum disorder (Fusar-Poli et al., 2022 In this article, we summarize the diagnostic relationship between autism and BPD and theorize about why misdiagnoses occur.
What causes BPD?
Research is still trying to piece together what causes personality disorders. So far, we know that genetics is the most influential predictor of BPD. One study estimated the heritability rate of BPD to be at 46%Familial risk and heritability of diagnosed borderline personality disorder: a register study of the Swedish population (Skoglund et al., 2021 This means that in the BPD population, you can explain 46% of the cause of their personality disorder with genetics. If you have BPD, chances are, a close relative does as well.
Environmental factors account for the remaining causes of BPD. One environmental factor that is often linked to BPD is a history of childhood trauma. While trauma might be a contributing factor, it cannot explain on its own why someone develops BPD. For example, it doesn’t explain why BPD traits persist across the lifespan, even following successful treatment for conditions like PTSD. There are also many individuals who did not experience high levels of childhood trauma but still go on to develop BPD. Most importantly, the majority of people who have experienced pervasive childhood traumas do not go on to develop BPD.
To summarize, while BPD is genetic and tends to run in families, your family history alone cannot predict whether you will develop BPD. Your chances of developing BPD increase depending on your environmental conditions. One such condition might be childhood trauma, though this relationship alone isn’t very strong.
What characterizes BPD?
Individuals diagnosed with BPD based on the DSM-5 (the Diagnostic and Statistical Manual of Mental Disorders) must exhibit at least 5 of the following 9 traits:Diagnostic and statistical manual of mental disorders (5th ed.) (American Psychiatric Association, 2013)
- Frantic efforts to avoid real or imagined abandonment
- Unstable and intense interpersonal relationships
- Identity disturbance, unstable self- image or sense of self
- Chronically feeling “empty”
- Impulsive behaviour across two areas in life (e.g. sex and substance use)
- Difficulty regulating emotions (often due to heightened reactivity in situations)
- Intense anger that is disproportionate to the situation
- Recurrent suicidal/self-harm behaviour
- Often feeling paranoid and dissociating in times of stress
In addition to the diagnostic traits,
here are some common features of BPD:
- Described as having the desire to recruit help—using charm to influence the situation
- Able to read social cues
- Aware of the opinion of others
- Able to ‘snap out’ of an outburst
- Angry if their needs are not being met
- Need for others to support their self-esteem
- Switch from idealizing someone to despising them instantly and without provocation
- Association with a childhood history of exposure to abuse, neglect, criticism and emotional invalidation
In contrast, here are some common features seen in autism:
- Lack of social understanding from an early age
- Greater difficulty reading social cues
- Needing time away from others; solitude is enjoyable
- Sensory sensitivity
- History of special interests
- Difficulty coping with change and transitions
- Self-harm and suicide attempts are less likely to be related to trying to influence others behaviours or bring the focus of attention onto themselves
Here is an overview/comparison of some of the traits of both neurologies:
BPD traits vs autistic traits
|Desiring to recruit help/using charm
|May mask autistic traits to fit in
|Can read social cues
|Difficulty reading social cues
|Aware of the opinions of others
|Lack of social understanding since childhood
|Able to “snap out” of an outburst
|Has meltdowns that can take a while to recover from
|Shows anger if needs are not met
|Becomes sad & isolates when needs are not met
|Need for external validation to regulate self-esteem
|May have weak self-esteem, but looks less for external validation
|Engages in idolization & devaluation
|Has a nuanced view of others & object permanence
Why are autistic traits often mischaracterized as BPD traits?
Several of the traits listed above also appear often in autistics.Borderline personality as a self-other representational disturbance, Bender and Skodol, 2021 Even though some BPD and autistic traits may seem similar on the surface, they are driven by differing underlying factors.
Let’s go through the DSM traits for BPD and investigate how an individual exhibiting these traits can easily be misunderstood as BPD, when in fact they may be autistic.
Frantic efforts to avoid real or imagined abandonment
This trait can occur in autism because autistics tend to make friends and lose them repeatedly. However, unlike in BPD, the issue of abandonment may be a reality for autistics because while we may be able to make friends, maintaining them is difficult.Loneliness, friendship, and well-being in adults with autism spectrum disorders, Mazurek (2014) As a result, a clinician might observe that we struggle to form and maintain relationships, but instead of realizing that this is likely caused by our difficulty understanding neurotypical social norms, they might assume it’s a trait of BPD.
Unstable and intense interpersonal relationships
Another common mix up stems from BPD individuals often repeating unhealthy patterns of behaviour in relationships.Correlates of autistic traits among patients with borderline personality disorder (Dell’Osso et al., 2018) Since many autistics tend to favour repetition, our behaviour can be misinterpreted as relating to BPD. While our preference for routines and repetition may negatively impact some of our relationships, this is related to our executive functioning difference in behavioural flexibility.‘I was just so different’: The experiences of women diagnosed with an autism spectrum disorder in adulthood in relation to gender and social relationships (Kanfiszer, Davies, & Collins, 2017)Underidentification of Autism Spectrum Disorder in Females: A Case Series Illustrating the Unique Presentation of this Disorder in Young Women (Trubanova et al., 2014)Autistic Cognition: Charting Routes to Anxiety (Stark et al., 2021)The overlap between autistic spectrum conditions and borderline personality disorder (Dudas, 2017)
In addition, autistics can be very intense in relationships. We often treat a friendship the same way we would another special interest. We want to invest a lot of time, attention, and energy into it. For a neurotypical, this can feel almost like stalking.
Until I made autistic friends, people found me overly enthusiastic about getting to know them. They would become a special interest for me. I would want to know everything about them. I would ask them to do numerous personality tests and ask them detailed questions about themselves. In part, this occurs because I make assumptions without detailed knowledge about a person. For example, my best friend did not tell me he went to the grocery store, so I assumed he was starving all the time except for meals his mom would give him, so I would often send him food. It was a shock to me to know that he did go shopping. – Natalie
Identity disturbance, unstable self-image or sense of self
In contrast to BPD, where these struggles are more generalized, autistics tend to struggle specifically with our sense of selves. For us, our sense of self is often based on perpetual criticism and rejection and a lack of compliments and inclusion from our peers. Consequently, our sense of self is often quite negative, particularly during our teenage years, which can be particularly destructive.Perceptions of social support and experience of bullying among pupils with autistic spectrum disorders in mainstream secondary schools, Humphrey & Symes (2010)Loneliness, friendship quality and the social networks of adolescents with high-functioning autism in an inclusive school setting, Locke, et al. (2010) For clinicians, an excellent tool to use in diagnosis is to ask the patient ‘Who are you?’. While non-autistics will tend to give a list of their social roles, autistics will struggle with the question, finding it difficult to answer.
I have contemplated the question of ‘Who am I?’ For me, it is simply too complex, too broad. But above that, I don’t know how I can define myself as I am ever-changing. I am not the same person I was when I began to write this post. I have some idea of what other people think of me, but that does not define me. On top of that, my autistic brain is designed to look for what is wrong, and as a result, tends to give an endless monologue of what it finds wrong with me. As an aside, I do not let it do that anymore; I understand that looking for errors is a strength in my work, but it is not helpful for me to criticize myself consistently. – Natalie
Yet another BPD trait that is seen in autism is impulsivity. This is especially common since impulsivity is also a frequent trait in ADHD and 40–70% of autistics have ADHD.ASD and ADHD Comorbidity: What Are We Talking About?, Hours, 2022
Recurrent suicidal behaviour, gestures, threats and self-mutilation
Likewise, autistics have high parasuicidal behaviour. One study found that two-thirds of autistic adults without intellectual disability said they had thought about suicide at some point, and 35% had made specific plans or made an attempt.Suicidal ideation and suicide plans or attempts in adults with Asperger’s syndrome attending a specialist diagnostic clinic: a clinical cohort study, Cassidy et al. 2014 One explanation for these behaviours is self-hatred, however at other times, autistics find that creating physical pain helps in counteracting emotional pain. Since affective instability due to a marked reactivity in mood is common in autistics, difficulty with self-regulation is a significant barrier to autistic mental health.
Feelings of emptiness
In contrast to BPD, chronic feelings of emptiness are less common in autism. Instead, autistics more commonly experience feelings of loneliness. Thus it may be useful for clinicians to inquire about these differential traits when comparing between BPD and autism.
Inappropriate, intense anger or difficulty controlling anger
Similar to BPD, autistics do tend to display this trait. But for us, this anger is a much-needed way for releasing huge amounts of energy. This can look like an externalizing (explode) or internalizing (implode) display of anger. Within the autistic community, this is most commonly referred to as a meltdown.The lived experience of meltdowns for autistic adults, Lewis & Stevens (2023) Without an understanding of the underlying trigger for a meltdown, such as an uncontrollable reaction due to sensory overwhelm, a clinician might assume that we have BPD because we display “intense anger that is disproportionate to the situation” or “heightened reactivity in situations”.
Transient, stress-related paranoid ideation
or severe dissociative symptoms
Just like in BPD, it can be common for autistics to appear paranoid. However, unlike BPD, our paranoia tends to originate from difficulties with reading people’s intentions. People’s harms can feel very deliberate with autism. If we are hurt, our difficulty with understanding social cues can easily lead us to think that this hurt was intentional.
I have a really hard time understanding that people are not lying to me or not being deliberate in their hurtful behaviour. For example, two friends who were a couple came out to dinner—Joe and Sue (not their real names). However, when they arrived at dinner, Sue was ill. The dinner was a miserable experience for me, as Sue was clearly very sick. I felt really angry at Sue. Irrationally angry. Despite her being sick, I felt she had been purposely trying to let me know she did not like coming out with me. I asked Joe why Sue had come to dinner sick. Joe explained that it was because Sue wanted me to like her, so she was worried about cancelling, and Sue being autistic, was used to masking. Once I understood the explanation, I settled down. I think part of this paranoia comes from the world being a confusing place for me, especially when people use white lies. These things I don’t understand have often led to me being rejected by other people. – Natalie
With BPD, stress-related paranoid thinking can cross into psychosis. In fact, the term ‘borderline’ came from clinical observation of people with BPD having psychotic thoughts, but not being psychotic themselves.Borderline personality disorder, Şenol (Encyclopedia Britannica, 2022 For example, as a clinician, I once encountered a person with BPD who became convinced that their three-year-old grandchild hated them because their grandchild wanted to play with his big brother. Despite my explaining that it is normal for a three year old to prefer to play with their big brother over their grandparent, the person with BPD could not comprehend this. No amount of explaining it could change their mind. At the same time, this person held a top managerial position.
One way clinicians can differentiate between the paranoid thoughts in BPD versus autism is to counter paranoid thoughts with evidence or explanation. With an autistic, an explanation of what is occurring will help them correct their understanding. In someone with BPD, it is more difficult to explain what they are seeing incorrectly as it is a form of psychosis, rather than a lack of social understanding.
In general, when clinicians incorrectly diagnose an individual with BPD instead of autism, they often overlook the underlying cause of these outward behaviours.Experience of mental health diagnosis and perceived misdiagnosis in autistic, possibly autistic and non-autistic adults (Au-Yeung et al., 2019) This happens most in autistics who mask and camouflage such that they “don’t look autistic” according to the stereotype.
Why are women more commonly misdiagnosed with BPD?
Autistic women have higher rates of misdiagnosis in part due to our nonstereotypical presentations compared to men.What misdiagnoses do women with autism spectrum disorder receive in the DSM-5? (Dell’Osso & Carpita, 2022) The way we present to the world is often a product of our higher levels of masking and camouflaging.Meta-analysis of neuropsychological measures of executive functioning in children and adolescents with high-functioning autism spectrum disorder (Lai et al., 2017)Protective effect or missed diagnosis? Females with autism spectrum disorder (Hull & Mandy, 2017) Women also have more social norms to adhere to in the neurotypical world, creating more opportunities for our social “missteps” to be attributed to BPD.
Generally, among women, there is a higher expectation to maintain interpersonal relationships. For example, in neurotypical social groups, women tend to have large superficial social networks. In contrast, autistics usually prefer having fewer closer relationships.‘It’s different for girls’: Gender differences in the friendships and conflict of autistic and neurotypical adolescents (Sedgewick, Hill, & Pellicano, 2019)Setbacks and Successes: How Young Adults on the Autism Spectrum Seek Friendship (Sosnowy, 2019) Additionally, when we want to build a relationship, we often single out the person we are attracted to, engage in deep conversations on specialized topics, and invite the other person to adopt our routines and interests. Since this is against neurotypical social norms, this is often viewed as an “unhealthy attachment”—a BPD trait. Thus, an undiagnosed autistic woman who struggles to fit in with her peers can easily be “flagged” as having BPD if a clinician doesn’t look at the underlying cause. In comparison, men don’t have as many social expectations, so an autistic man’s non-neurotypical social patterns do not get “flagged” as readily.
Another common cause of misdiagnosis in women is based on our often high motivations to fit in with these social norms. When we work hard to camouflage by practicing social scripts, but inevitably still struggle in relationships with neurotypicals, clinicians may view this as the BPD trait of intensely fearing abandonment.Gender Differences in the Social Motivation and Friendship Experiences of Autistic and Non-autistic Adolescents. J Autism Dev Disord., Sedgewick 2016Sex Differences in Autism Spectrum Disorders Across the Lifespan, 2019 This “fear of abandonment” can also be mischaracterized in instances where we experience distress if a friend cancels last-minute plans. For most autistics, our distress isn’t driven by a fear of abandonment but rather an executive functioning difference. We don’t cope well with sudden changes to our plans, irrespective of who they are with.
Moreover, our higher levels of camouflage often cause us to struggle with our sense of self because we are forced to act in inauthentic ways.The Experiences of Late-diagnosed Women with Autism Spectrum Conditions: An Investigation of the Female Autism Phenotype (Bargiela, Steward, & Mandy, 2016)Protective effect or missed diagnosis? Females with autism spectrum disorder (Hull & Mandy, 2017) However, our lack of self-identity is rooted in this forced inauthenticity, not based on an unstable identity personality trait which is often seen in BPD.
One important consideration in this discussion is that to date, research has done a poor job regarding autism and gender identity. Due to the lack of data collection on this topic, we still don’t know how BPD misdiagnosis affects gender-diverse individuals. This is particularly frustrating since we know that a large proportion of the autistic community is gender-diverse.Elevated rates of autism, other neurodevelopmental and psychiatric diagnoses, and autistic traits in transgender and gender-diverse individuals (Warrier et al., 2020) Since the diagnostic criteria for autism are biased towards a stereotypical presentation of autism—mainly seen in (white) cis-gendered boys—and gender-diverse individuals also mask and camouflage a lot, my assumption is that the rate of BPD misdiagnosis is likely also high in gender-diverse autistic populations.
Brain differences in BPD versus autism
Brain imaging is still in its infancy and can only be used retrospectively, rather than diagnostically.Neuroimaging and Mental Illness: A Window Into the Brain, NIMH, 2023 While current scopes of knowledge limit our ability to use imaging to diagnose conditions like autism, it can be used to differentiate a tumour from depression. That said, scientists are continuously advancing brain imaging capabilities by collecting data from brain scans of people who are diagnosed with conditions, including autism.
Thus far, there are a number of brain differences between autism and BPD that have been identified. The list below is not comprehensive, but it does illustrate a few notable divergences.
- BPD: smaller amygdala.The Neurobiology of Borderline Personality Disorder, Pier, 2020
- Autism: larger right and left absolute and relative amygdala volumes than the control group.Abnormal development pattern of the amygdala and hippocampus from childhood to adulthood with autism Author links open overlay panel, Xu, 2020
Hippocampus—learning and memory
- BPD: right hippocampus gray volume decreases.The Neurobiology of Borderline Personality Disorder, Pier, 2020
- Autism: right absolute hippocampal volume of autistic patients was also larger than that of neurotypical adults, but not after controlling the total brain volume. The hippocampal volume is larger in autistic children and adolescent autistics.Abnormal development pattern of the amygdala and hippocampus from childhood to adulthood with autism Author links open overlay panel, Xu, 2020
Using changes in brain activity to assess the ability to self-reflect on cause and effect
- BPD: Frontal lobe differences interfere with self-referential processing. In simpler language, people with BPD have a challenge understanding the cause-effect nature of their behaviour. their Specifically people with BPD have difficulty understanding that their behaviour resulted in an undesired outcome.Reduced neural differentiation between self-referential cognitive and emotional processes in women with borderline personality disorder, Scherpiet et al., 2015
- Autism: No associations were found between self-referential processing and autism. Autistics do have the ability to self-reflect and hypothesize about the cause and effects of their actions on others.Self-Referential Processing Predicts Social Cognitive Ability, Dinulescu, 2020 It is interesting to note that researchers had initially hypothesized that autistics would be unable to self-reflect and were surprised by their findings.
Co-occurrences between BPD & autism
Earlier we debunked how seemingly overlapping traits between autism and BPD can be differentiated based on understanding the underlying cause for these behavioural patterns. But what about in a case where an individual is diagnosed with BPD and autism? A recent analysis looking at co-occurrences of BPD and autism found that data was inconsistent across studies, suggesting that co-occurrences may or may not make sense given each set of behavioural traits.Overlap of autism spectrum disorder and borderline personality disorder: A systematic review and meta-analysis (May et al., 2021) Therefore is there legitimacy for these dual diagnoses?
Is PTSD the common factor?
Both the autistic population and the BPD population have higher incidence rates of childhood trauma.Autism Spectrum Disorder and Post-Traumatic Stress Disorder: An unexplored co-occurrence of conditions (Haruvi-Lamdan et al., 2020)Comorbidity between post-traumatic stress disorder and borderline personality disorder: a review (Frías & Palma, 2015) This means that many autistic and BPD individuals likely display symptoms of PTSD. In fact, many BPD traits mirror the symptoms of PTSD. For example, both the diagnostic criteria for BPD and PTSD include dissociation, emotional dysregulation, and high levels of angerComplex PTSD and borderline personality disorder (Ford & Courtois, 2021) Since clinicians can overlook our autistic traits as BPD traits, and many BPD traits mirror the symptoms of PTSD, one likely scenario is that a dual diagnosis of autism and BPD is actually autism and PTSD.
Is the differing factor self-reflection?
As a consequence of the high degree of diagnostic overlap, an important task for clinicians becomes differentiating one diagnosis from the other. One common trait across all personality disorders is a reduction in self-reflection. This means that many individuals with BPD struggle to think about their own thinking.Metacognition and Mentalizing in the Psychotherapy of Patients With Psychosis and Personality Disorders. Journal of Clinical Psychology., Dimaggio G, Lysaker PH., 2015 Notably, a reduction in self-reflection is not associated with autism. Therefore, a dual diagnosis may be valid if you’re an autistic who relates to the traits of BPD, and if you struggle to self-reflect.
What about attachment?
Another feature of BPD not associated with autism is volatility within relationships. Someone with BPD can struggle with relationships because they may feel really close to someone in one instance, but then feel harmed by them a few moments later. This creates an unstable attachment bond which leads to some of the traits listed in the DSM such as avoiding real or imagined abandonment. Thus you may be an autistic with BPD if how you feel your relationships are unpredictable and you flip-flop between extremes, such as feeling loved/cared for and feeling attacked/harmed.
Psychometrics for BPD
Since there seems to be so much overlap between BPD traits and other diagnoses, can we trust the psychometric tests used to diagnose BPD? Below are some examples of questionnaires that are useful for figuring out if a formal diagnosis of BPD is warranted.
McLean Screening Instrument for BPD (MSI-BPD)
This 10-item questionnaire is a commonly used screening tool for BPD.A Screening Measure for BPD: The McLean Screening Instrument for Borderline Personality Disorder (MSI-BPD) (Zanarini, 2003) A score of 7+ has been shown to be indicative of BPD. This questionnaire has been shown to be reliable (this means that it is consistent in its ability to measure BPD likelihood) and valid (this means that it accurately measures the traits associated with BPD and not other diagnoses). If you’re interested, here’s a link to check out the MSI-BPD:
Screening Instrument for BPD (SI-Bord)
Each of the 5-items on this self-report questionnaire for BPDDevelopment and validation of a screening instrument for borderline personality disorder (SI-Bord) for use among university students (Lohanan, 2020) is scored out of 4. Based on a cut-off score of 9+ in total, this screening tool was also shown to have high reliability and validity in a sample of university students. This screening tool is fairly new, but so far it seems to be a promising quick way to suggest whether seeking a formal diagnosis of BPD is justified.
If scores on either of these questionnaires are above the threshold, clinicians will likely use the Structured Clinical Interview for DSM-5 Personality Disorders (SCID-5-PD) as the official clinical interview for diagnosing BPD.Structured Clinical Interview for DSM-5® Personality Disorders (SCID-5-PD)., Smith This is comparable to the ADOS-2 clinical interview that Embrace Autism uses to formally diagnose autism.The Autism Diagnostic Observation Schedule, Module 4: Revised Algorithm and Standardized Severity Scores, Hus, 2015
Values in Action Inventory of Strengths (VIA-IS)
Another psychometric questionnaire is the VIA-IS. It looks at personality traits and has been used to investigate personality characteristics consistent with different conditions. Below you can see traits that are low and high in BPD and in autism.The Underuse and Overuse of Character Strengths in Borderline Personality Disorder Symptoms, Seligman, 2023
VIA-IS Character Strengths underused in:
- BPD: kindness, honesty, self-regulation, prudence, perspective, and love
- Autism: self-regulation, zest, leadership, teamwork, social intelligence
VIA-IS Character Strengths overused in:
- BPD: social intelligence, judgment, bravery, curiosity, and zest
- Autism: honesty, love of learning, perspective, judgement, fairness, prudence
Based on the patterns in character strengths found using the VIA-IS, in many ways, these two conditions are very different. However, BPD and autism do share a high score in judgement and a low score in self-regulation. Using these character strengths and weaknesses, clinicians can further support the reliability and validity of their diagnoses.
- BPD is a personality disorder caused by a combination of genetics and environmental factors.
- BPD is a common misdiagnosis in autistics
- Even though on the surface some BPD and autistic traits may seem similar, they are driven by differing underlying factors
- Autistic women have higher rates of misdiagnosis with BPD
- This is primarily because there is a higher expectation for women to conform to neurotypical social norms
- When an autistic woman isn’t able to camouflage with her peers, she may get “flagged” as BPD
- Misdiagnoses can occur due to PTSD
- Diagnostic criteria for BPD overlap with PTSD
- Many autistics have experienced high levels of trauma and will therefore fit the diagnostic criteria
- A small proportion of autistic individuals may also have BPD if they struggle to self-reflect or experience volatility within relationships
- The current assumption is about 10% of autistics have co-occurring BPD
- The MSI-BPD and the SI-Bord are two simple screening questionnaires that can be used to suggest whether an individual may have BPD
- The VIA-IS can be a useful way to bolster clinical diagnoses by comparing common character strengths in BPD versus autism